The present invention relates in general to a delamination apparatus and method, and more particularly to apparatus and a method for separating layers of a laminar film unit containing laminar imaging material.
The prior art contains many devices and methods for separating layers of laminar film units, for instance, for the purpose of rendering a developed image visible. Such apparatus and methods are commonly used in connection with so called peel apart film units and may utilize a blade or other element insertable between two predetermined layers or sheets of a film unit fixed to the periphery of a rotating drum, for instance that disclosed in U.S. Pat. No. 4,670,085.
Such prior art apparatus and methods may be characterized as providing a peeling action, for instance removal of one layer from another. They would not however be suited for providing delamination as understood in the context of the present invention. Delamination in the sense used herein, is to be understood as meaning a process of separating cover or support sheets from opposite surfaces of a vertically frangible layer each carrying different portions of the frangible layer with it as determined by the strength of an adhesive bond at any given point between the surfaces of the layer and the respective sheet. Vertical frangibility of the layer as used herein is intended to mean the ability of the layer to break in a direction normal to its surface but to exclude breaking of the layer between its surfaces.
In U.S. patent application Ser. No. 07/616,796, filed Nov. 21, 1990, there is disclosed a device for accomplishing a delamination as described above wherein apparatus is provided for delaminating a composite sheet structure comprising complementarily adjoined portions of a frangible layer adhesively bonded to a pair of sheets, the structure having a marginal portion attached to one and extending beyond the other of the sheets. The apparatus comprises a first roller means having an axially extending slot in its peripheral surface, second roller means positioned in parallel to the slot, and means for inserting the marginal portion into the slot and further means for rotating the first roller in a direction winding one sheet on the first roller and moving the other sheet away from the first and second rollers.
While the device and method disclosed have proved successful, the present invention has an objective to provide an improved process and method to accomplish the delamination of a composite sheet structure such as that which is described in the aforementioned U.S. patent application.
It is therefore an object of the invention to provide apparatus and method for delaminating a composite sheet structure comprising a plurality of selectively releasable superposed sheets.
A further object of the invention is to provide a novel apparatus for delaminating a composite sheet structure of the aforesaid kind in such a manner that predetermined portions of a frangible layer interposed between, and releasably connected to two sheets, are provided on one of the sheets with complementarily adjoining portions of the layer provided on the other sheet.
Yet another object of the invention is to provide apparatus and method for separating two sheets enclosing between them a layer of an image forming substance, to remove predetermined portions from the layer thereby to form two complementary images.
And yet a further object of the invention is to provide a novel delamination apparatus and method which makes possible a selective removal of portions of a frangible layer by sheets adhered to opposite surfaces of the layer.